Patent GB-713114-A (GB)
Abstract: 713,114. Recording-apparatus. BENDIX AVIATION CORPORATION. Jan. 2, 1952 [Jan. 12, 1951], No. 185/52. Addition to 675,867. Class 106 (4). [Also in Group XXXVIII] The stylus structure of the parent Specification is modified in that the means for bending the resilient stylus member so as to deflect its free end comprises a guide member, positioned in front of the record blank adjacent and parallel to the scanning path and in the plane o rotation of a portion of the stylus member, for contacting this portion of the stylus member during the scanning part of each revolution, thereby deflecting the traversing end into substantially linear travel through the scanning path. The invention is shown in an echo-sounding depth recorder, (see Group XXXVIII), which comprises a paper tape 10 slowly unwound from a roll 11 and drawn across a backing plate 12 by feed rollers 13, 14 and out of the case 16 through a slot 15, Fig. 1. The roll 11 rests on a flange of a supporting supply roller rotatable in a socket 18 in the base 19 and a braking action is supplied by a curved leaf spring 20 bearing on the outer periphery of the roll 11 with a constant force irrespective of the amount of paper on the roll. A hole 20a in the spring 20 engages the top 17b of the supply roller and its other end is clamped by a nut 25 above a helical spring round an adjacent post so that the braking force can be adjusted by the nut 25. The feed roller 13 is preferably knurled at the centre 13a, Fig. 2, and is supported in bearing apertures in the base 19 and in a plate 27 supported by posts 28, 29. A small constant-speed electric motor 30 with gear case for reducing the speed of its output shaft 30a drives the feed roller 13 through a tongue and groove coupling 30b. The idler roller 14 may be rotatably supported in a yoke 32, Fig. 3, which is pivotally supported on a post 33 and a torsion spring 34 urges the roller 14 against the paper tape 10 and drive roller 13. A spring wire stylus member 36 is carried by a drum 37 and its tip 36a in contact with the paper 10 is guided during rotation of the drum 37 by a portion 36b engaging a closed track member 38 whose long straight section causes the tip 36a to traverse the paper in a straight line at constant speed. The track 38 is welded or brazed to a web 40 upstanding from a track base 41 pivotally held against the base 19 by a screw 43. An upstanding pin 44 at the other end of the track base 41 engages a slot 45a in one end of a lever 45 pivoted to the base 19 by a screw 46. The tip 36a of the stylus member may be adjusted with respect to the paper by moving the lever 45 to shift the track 38. The drum 37 is mounted on the shaft 48 of a constant speed motor 49 and between the motor 49 and drum 37 and concentric with the shaft 48 is mounted a commutator structure 50, yieldably held against rotation by spring clips 51, with a handle 52 for facilitating phasing adjustment. One end 36c of the stylus member 36 extends from the drum 37 against the face of the commutator 50 to form a brush to co-operate with segments 50a, 50b, 50c and 50d to control the electric circuit of the depth recorder. The stylus member 36 may be attached to the drum 37 by springing a loop 36d into a recess 37a and the brush portion 36c may extend from the side of the drum 37 through a slot 37b extending from the recess 37a. The stylus member 36 may be a simple spring wire but in order to secure accurate tracking in a straight line at constant speed it may be desirable for the stylus member to have greater yieldability to longitudinal bending round the drum at its end nearest the drum whilst still being relatively stiff to bending parallel to the axis of the drum and for this purpose the stylus member may be strip sheet stock as shown in Fig. 5 with a slot 361a widest near the drum so that the cross-sectional area is least near the drum or it may be formed as shown in Fig. 6. The records 10a and 10b on the tape 10 are formed by electrical discharge and therefore the stylus member 36 and the track 38 are insulated from the frame of the instrument. Desired contacts are made through the brush 36c and commutator 60 and through a double throw switch the depth range of the recorder may be doubled.